1. Field of the Invention
The present invention is generally in the field of electrical circuits. More specifically, the present invention is in the field of cable drivers.
2. Background Art
Cable drivers are used to amplify and transmit data signals, such as video or audio, through interconnect cables from one device to another. For example, in professional video applications such as operating a television or broadcast studio, several devices with multiple input and output ports may need to be interconnected, including routers, distribution amplifiers, and switchers. As supporting infrastructure continually expands to support more devices and port interconnections, it becomes increasingly important to optimize the power consumption of the cable drivers in such devices to reduce operating costs and improve reliability. Furthermore, with the proliferation of high bandwidth video such as high definition 1080P video and the adoption of the 3G-Serial Digital Interface (SDI), it is also increasingly important to improve the output return loss (ORL) of the cable driver to preserve the quality of the transmitted signal.
Conventionally, current mode output stages are used in such video cable drivers. However, current mode output stages require undesirably high levels of power consumption and typically require large output transistors, which undesirably degrade ORL, especially at high bandwidth 3G-SDI data transmission rates. One known method of mitigating ORL degradation in conventional current mode cable drivers utilizes external inductance and resistance on the outputs. However, this method undesirably requires external components and custom tuning for each particular application.
Accordingly, there is a need to overcome the drawbacks and deficiencies in the art by providing a cable driver output stage with low power consumption and improved ORL suitable for various high bandwidth data transmission applications.